Lifting-jack



W. S WILKINS.

LIFTING JACK.

APPLICATION FILED MAR; 31. 1920- Patented May 3L 1921i.

nti iTE LIFTING-JECK.

Specification of Letters, Patent.

Patented May 31, 1921.

Application filed March 31, 1920. Serial No. 370,220.

T 0 all w ham it may concern:

Be it known that I, WALTER SAMUEL W1L- KINS, a subject of the King of Great Britain, residing at Hill View, Kings Hill, Wednes bury, in the county of Stafi'ord, England, have invented certain new and useful Improvements in Lifting-Jacks; and I do here by declare the following to a full, clear, and exact description of the same.

This invention relates tolifting jacks com-- prising a casing containing a vertically mov-- able pillar having a toothed rack along one edge, a pivoted socket to which may be fitted an operating lever, the socket being mounted in the casing and carrying at its inner end an actuating pawl adapted to engage with the rack, a second or retaining pawl for keeping the pillar stationary when the actuating pawl is not in engagement with the rack, a spring acting upon both pawls, and means for adjusting this spring so as to cause the pawls either to lift or to lower the pillar when the lever is reciprocated.

According to the present invention the actuating and retaining pawls are acted upon by a curved plate spring which has one end attached to each pawl and the end of the operating lever is arranged to exert pressure upon said spring, means being provided for retaining the operating lever in either of two alternative positions in the pivoted socket, in one of which when the lever is reciprocated, the pawls operate to lift the pillar and in the other of which the pawls operate to lower the pillar. This construction is particularly convenient in use inasmuch as the change from lifting to lowering or from lowering to lifting can be effected by pulling or pushing the end of the operating lever which is usually much more easily accessible than the rest of the apparatus when the jack is in use Referring to the drawings Figure 1 is a sectional view in side elevation showing the operating lever in the position it assumes when the jack is being used for lifting.

F i 2 is a fragmentary section on line A- of Fig. 1.

Fig. 3 is a similar view to Fig. 1 showing the positions of the parts when the jack is being used for lowering.

In the construction illustrated the casing 1 may be pressed from sheet metal and may be made in two parts, an upper part 1 bent into channel section and a lower part 2. The upper part may be secured by riveting to the base 2. The part 1 is bent to channel section and the parallel flanges of the channel may be connected together by bolts such as 3 partly surrounding which may be arranged distance plates such as 4;.

The casing 1 accommodates a pillar 5 which is used for lifting, the upper end of the pillar being fitted with a member 6 which has a curved upper surface 7 suitable for engaging with an axle or other member. The

pillar 5 may carry a projecting rivet 8 engaging in a slot 9 in the casing 1 whereby the pillar is guided and its vertical movement limited.

The pillar 5 is provided with a rack 10 having buttress teeth.

The casing l carries a socket 11 which is pivoted to the casing at 12. To the inner end of the socket 11 is pivotally mounted at 18 an actuating pawl 14, while a retaining pawl 15 is pivotally mounted upon the pin 12. Thus when the socket 11 is turned on its pivot 12 the pawl 14 moves bodily up and down while the pawl 15 has no movement.

The pawl 14 is provided with a laterally projecting pin 16 and the pawl 15 is provided with a laterally projecting pin 17, and engaging with the pins 16 and 17 is a curved plate spring 18.

Pivotally mounted to the casing at 19 is a lever 20 which bears upon the back of the spring 18. The lever 20 is adapted to be moved by the end 21 of the operating lever 22 which is inserted in the socket 11. Means is provided for retaining the operating lever 22 in either of two positions relative to the socket. The lifting position is shown in Fig. 1 in which the end 21 of the lever is pressing upon the lever 20 which is acting directly upon the spring 18 so as to force both pawls into engagement with the rack 10. The lowering position is shown in Fig. 3 wherein the lever 20 is free to move away from the spring 18. The means employed for looking or retaining the lever 22 in either of its two positions are such that the lever can be forced into the socket by holding the free end of the lever and as it enters the socket it will first snap into the lowering position while further pressure will cause it to move farther into the socket so that it will finally snap into the lifting position. It can be adjusted back into the lowering position by pulling the lever partially out of the socket until it again snaps into said position. This action is effected by providing a spring 23 riveted to the lever at 24. The end of this spring is slotted as shown at 25 and this'slot is adapted to engage with rojeotions 26 and 27 upon the socket 11. s the end of the lever 22 enters the socket 11 the end of the slot 25 rides up the inclinedsurface of projection 26 until it finally passes over the point of the projection 26. When this happens the lowering position of the lever has been attained. Further pressure on the end of the lever 22 will cause the end of the slot 25 to rise up'the inclined surface of the projection 27 until finally the end of the socket 25 will pass over the point of the projection 27. This is the lifting position of lever 22. Return movement is effected by pulling the lever 22 when the end of slot 25 will ride up the inclined surface 28 of projection 27 and pass over the point of the projection 27 until it meets the vertical face 29 of projection 26 when the lowering position of lever 22 will again have been reached. The socket 11 may in some cases be made from pressed sheet metal and the projections 26 and 27 may be made integral therewith or may be made separately and attached thereto.

In operation assuming the lever 22 to have been adjusted into its lifting position as shown in Fig. 1, the end 21 of lever 22 is pressing upon the lever 20 which is transmitting the pressure to the spring 18. lVhen in this position the spring 18 is tending to force both pawls 14 and 15 into engagement with the rack 10. When the free end ofward. The rack however is retained against downward movement by the pawl 15 and the pawl 14 continues to move downwardly until its point clears the point of the tooth with which it is in engagement. When this occurs the end of the pawl 14 is forced under the horizontal surface of the tooth by the spring 18. Thus so long as the lever 22 is reciprocated about its pivot 12 the pillar 5 will be lifted with a step by step movement. When under compression.

it is desired to lower the pillar 5 the lever 22 is moved into its lowering position as shown in Fig. 3. The lever 20 is now free to move away from the back of spring 18. When the parts are in the position shown in Fig. 3 and the freeend of lever 22 is moved downwardly, the pawl 14 moves bodily upward. As the pawl 14 moves upward the ends of spring 18 are moved toward each other thus placing the spring Near the end of the upward movement of the pawl 14 its end engages in a tooth, and at the extreme end of its upward movement the pawl 14 actually produces a slight lifting motion on the pillar 5 thus releasing the awl 15 from downward pressure arising from the load on the pillar. As soon as the pawl 15 is released of this downward pressure the spring 18 being under compression forces the pawl 15 out of engagement with the rack. The pawl 15 then takes up the position shown in Fig. 3, clear of the rack. The motion of lever 22 is now reversed, the free end being moved upwardly. The pawl 14 now moves bodily downward'allowing the pillar 5 to move downwardly with it. As the pawl 14 moves downwardly the ends of the spring 18 are moved apart, and near the end of the downward movement of pawl 14 the ends of spring 18 are separated by more than their normal distance so that the upper end has a tendency to move toward the lower end. This tendency causes pawl 15 to move to the left with its point engaging the incline of one of the teeth of rack 10. At the end of the downward movement of pawl 14 the point of pawl 15 engages under the horizontal surface of the rack 10 thus supporting the load on the pillar 5. Im- 105 mediately after the pawl 15 commences to take the load, the pawl 14, being freed from pressure due to the load on the pillar 5, is moved clear of the rack by the spring 18, the ends of which are now endeavoring to 110 regain their normal positions. As soon as the end of pawl 14 has moved clear from the rack, the motion of the lever 22 is again reversed and the pawl 14 commences to move bodily upward while the pawl 15 re 115 tains the pillar 5 against dropping under its load. This action continues until, at a point near the end of the upward move ment of pawl 14, the spring 18 being by this time under compression, forces the end 120 of pawl 14 to the left so that it again engages with the rack. This lowering move ment will continue as long as the lever is reciprocated and is in the position shown in Fig. 3. 125

What I claim then is 1. A lifting jack comprising a casing containing a vertically movable'pillar having a toothed rack along one edge, a pivoted socket to which may be fitted an operating lever, 130

the socket being mounted in the casing and carrying at its inner end an actuating pawl adapted to engage with the rack, a retaining pawl for keeping the pillar stationary when the actuating pawl is out of engagement with the rack, a curved plate spring having itsends attached respectively one to each pawl, means for retaining an operating lever in either of two alternative positions in said socket, in one of which said lever will exert pressure upon said curved spring tending to force both pawls into engagement with the rack, and in the other of which said pressure is removed from the curved sprin 2. A lifting jack comprising a casing containing a vertically movable pillar having a. toothed rack along one edge, a pivoted socket to which may be fitted an operating lever, the socket being mounted in the easing and carrying at its inner end an actuating pawl adapted to engage with the rack, a retaining pawl mounted upon the same pivot as said socket for keeping the pillar stationary when the actuating pawl is out of engagement with the rack, a curved plate spring having its ends attached respectively one to each pawl, means for retaining an operating lever in either of two alternative positions in saidsocket, in one of which said lever will exert pressure upon said curved spring tending to force both pawls into engagement with the rack, and in the other of which said pressure is removed from the curved spring.

3. A lifting jack comprising a casing containing a vertically movable pillar having a toothed rack along one edge, a pivoted socket to which may be fitted an operating lever, the socket being mounted in the easing and carrying at its inner end an actuating pawl adapted to engage with the rack, a retaining pawl for keeping the pillar stationary when the actuating pawl is out of engagement with the rack, a curved plate spring having its ends attached respectively one to each pawl, a pivoted arm bearing upon said spring and having a portion disposed within said socket, means for retaining an operating lever in either of two alternative positions in said socket, in one of which said lever will exert pressure upon said curved spring through the medium of said arm, said pressure tending to force both pawls into engagement with the' rack, and in the other of which said pressure is removed from the curved spring.

4,. A lifting jack comprising a casing containing a vertically movable pillar having a toothed rack along one edge, a pivoted socket to which may be fitted an operating lever, the socket being mounted in the easing and carrying at its inner end an actuating pawl adapted to engage with the rack, a retaining pawl for keeping the pillar stationary when the actuating pawl is out of engagement with the rack, a curved plate spring having its ends attached respectively one to each pawl, an operating lever adapted to be inserted in said socket, means including a pair of spaced projections upon said socket, one of said projections having two inclined sides and the other having one side inclined and the other substantially at right angles to the length of the socket and a slotted spring upon said lever cooperating with said projections to retain the operating lever in either of two alternative positions in said socket, in one of which said lever will exert pressure upon said curved spring tending to force both pawls into engagement with the rack, and in the other of which said pressure is removed from the curved spring.

5. A lifting jack comprising a casing containing a vertically movable pillar having a toothed rack along one edge, a pivoted socket to which may be fitted an operating lever, the socket being mounted in the casing and carrying at its inner end an actuating pawl adapted to engage with the rack, a retaining pawl for keeping the pillar stationary when the actuating pawl is out of engagement with the rack, acurved plate spring having its ends attached respectively one to each pawl, a pivoted arm bearing upon said spring and having a portion disposed with in said socket, an operating lever adapted to be inserted in said socket, means including a pair of spaced projections upon said socket, one of said projections having two inclined sides and the other having one side inclined and the other substantially at right angles to the length of the socket and a slotted spring upon said lever cooperating with said projections to retain the operating lever in either of two alternative positions in said socket, in one of which said lever will exert pressure upon said curved spring through the medium of said arm, said pressure tending to force both pawls into engagement with the rack, and in the other of which said pressure is removed from the curved sprlng.

6. A lifting jack comprising a casing containing a vertically movable pillar having a toothed rack along one edge, a pivoted socket to which may be fitted an operating lever, the socket being mounted in the casing and carrying at its inner end an actuating pawl adapted to engage with the rack, a retaining pawl mounted upon the same pivot as said socket for keeping the pillar stationary when the actuating pawl is out of engagement with the rack, a curved plate spring having its ends attached respectively one to each pawl, a pivoted arm bearing upon said spring and having a portion disposed within said socket, an operating lever adapted to be inserted in said socket, means including a pair of spaced projections upon said socket, one of said projections having two inclined sides and the other having one side inclined and the other substantially at right angles to the length of the socket and a slotted spring upon said lever cooperating with said projections to retain the operating lever in either of two alternative positions in said socket, in one of which said lever will eXert pressure upon said curved spring through the medium'of said arm, said pressure tending to force both pawls into engagement 10 with the rack, and in the other of which said pressure is removed from the curved spring. In witness whereof I afiix'my signature. WALTER SAMUEL WILKINS. 

